Mucus lines the mucosal epithelium along the airways and gastrointestinal and urogenital tracts, forming a barrier that is the body's first line of defense against pathogens, including viruses, bacteria and fungi, many of which are opportunistic. However, the protection afforded by mucins may be more than simply a physical barrier. Mucins, the heavily glycosylated glycoproteins that are responsible for the viscous, jelly-like properties of mucus, actively influence the virulent state of the microbes with which they come in contact.
Mucins are emerging as important regulators of microbial virulence that can prevent the expression of virulent traits of microbes, allowing these organisms to exist harmlessly inside a host organism, such as a human. For example, the human cell-surface mucin MUC1 can inhibit surface adhesion of the gastric bacterium Heliobacter pylori. Also, the secreted human mucin MUC5AC can prevent Pseudomonas aeruginosa surface attachment and biofilm formation by promoting a dispersive state of bacteria (Caldara, M. et al., Curr. Biol. 22:2325-2330 (2012)), can modulate HIV-1 (Bergey, E. J. et al., J. Acqui. Immune Defic. Syndr. 7:995-1002 (1994)) and influenza infectivity (Couceiro, J. N. et al., Virus Res. 29:155-165 (1993)).
Microbes, such as pathogens, seldom exist in isolation, and typically are in contact with other microorganisms, usually other microbes, within a host organism. To antagonize or compete against each other, microbes generally employ a variety of strategies, many of which are virulent. Currently, methods and compositions to prevent dominance of microorganisms for therapeutic purposes include administration of compositions, such as antibiotics, that eradicate microorganisms and can lead to an imbalance of the normal microorganism environment.
Maintaining physiologic homeostasis in higher animals, such as humans, requires a balance between the effects of microorganisms they host. An imbalance between interactions between different microorganisms can alter biological activities and disturb that homeostasis, such as by reducing cell viability, as measured by rates of cell growth and cell death.
Thus, there is a need to overcome or minimize problems associated with cell viability affected by intercellular interaction among different microorganisms.